Two main methods for the bending of longitudinal profiles are free-form bending and draw bending. In a device for draw bending, the longitudinal profile is taken up at the front end and drawn around a template, wherein the template specifies the bending radius. The decisive disadvantage with draw bending lies in the fact that the longitudinal profile can be bent within a radius only in one plane. The bending radius is also restricted when it is determined by the template. By contrast, with a device for free-form bending, there are many degrees of freedom available. In particular, in a device for free-form bending without the adaptation of device parts, both different and constant bending radii can be achieved, as well as variable radii as space curves. A disadvantage, however, is seen in the high apparatus expenditure required for this, and the downwards limitation due to small radii.
One known device for free-form bending (DE 697 22 944 T2) differs from the device described in the preamble in that the axial sleeve guiding the longitudinal profile is arranged stationary, and thus its distance interval in relation to the bending sleeve is not adjustable. The bending sleeve is mounted on a cross-slide, with which it can be adjusted in two orthogonal axes arranged transverse to the longitudinal axis of the longitudinal profile. In addition to this, the bend guide element can be pivoted about two axes running relative to one another and perpendicular to the axis of their passage aperture. Finally, it can be rotated about the axis of its passage aperture. For all these movement possibilities, individual drives and bearings are provided. In order to accommodate these parts at the bend guide element, a substantial amount of space is required. This space imposes a not insubstantial limit on the smallest possible bending radius. In addition to this, the expenditure on the technical mechanical engineering resources is relatively high.
With a known device for the free-form bending of the type referred to in the preamble (DE 102 49 315 A1), the bending sleeve is likewise mounted on a cross-slide, so that it can be adjusted in two orthogonal axes transverse to the longitudinal axis of the longitudinal profile. In addition to this, the bending sleeve can be pivoted about an axis running perpendicular to the axis of its passage aperture. Finally, it can be rotated about the axis of its passage aperture. As with the known device described heretofore, a substantial amount of space is required to accommodate all these parts and drives, at the expense of the smallest possible bending radius. The technical mechanical engineering arrangement is also correspondingly elaborate.